Hello everyone. What can be said about viscous abundant transparent ph…

Hello everyone. What can be said about viscous abundant transparent phlegm? A child has a cough that even leads to vomiting reflex. Yesterday he ate and vomited. Once, then it was not like this. I think it's from phlegm. Is it worth doing inhalation with physical solution at such symptoms? Will it get worse? It is currently weekend, doctors are not in touch.